Access brokers are making it easier for ransomware operators to attack businesses

Cyber security researchers have uncovered a new underground business model dubbed 'access-as-a-service' in which access to an organisation's network is sold rather than an exploit or zero-day vulnerability.

So-called access brokers are selling direct access to a company's network in which they're already embedded via shared remote VPN connections. Attackers can pay different sums for varying levels of access.

The business model, discovered and detailed by Trend Micro, could lead to a new way for ransomware operators to launch attacks without having working exploit themselves.

Attackers are now able to buy their way into a network, paying only as much as they need for the right level of access to achieve their objective.

The business model relies on stolen credentials for access brokers to have a viable service and Trend Micro said businesses will have to place a greater emphasis on protecting credential theft to avoid future breaches.

"Access brokers in the criminal underground often advertise this service like it’s a cinema ticket: Somebody buys this ticket, and they get straight in," read the report. "In reality, however, things are a bit different.

"For example, what exactly do customers get in exchange for their money? Sometimes, it’s access to a web shell or a similar straightforward method of getting a command prompt into the compromised network. More often than not, however, it’s just a set of credentials and a VPN server to connect to."

Remote Desktop Protocol (RDP) access and VPN-based access were the two most common products being advertised, primarily in the United States, Spain, Germany, France, and the UK.

After viewing more than a thousand adverts for services online, the most common targets Trend Micro observed were universities and schools (36%), 11% offered access to manufacturing firms and professional services, with other miscellaneous companies comprising the remainder.

Online adverts typically offer access to a company with a broad description such as 'big German energy company', offer details of the level of access available, type of access on offer (RDP or VPN), cost of the service, and in some cases details of the company's turnover and employee numbers.

Prices for services can range between a few US dollars for access to a single machine and six-digit sums for admin credentials to an entire business, but most dedicated brokers don't advertise their prices openly, according to the researchers.

Access brokers are typically advertising their products either on deep web criminal marketplaces, through a network of connections throughout underground forums, and in less common cases dedicated online shops are used for smaller-scale, single-machine access.

Trend Micro made several suggestions for businesses wary of being exploited using this new business model. Monitoring public breaches can be useful in determining if credentials may have been stolen and triggering a password reset for all staff if one is detected.

Enabling two-factor authentication (2FA) for remote staff will also help prevent remote access from criminals, as will closely monitoring user behaviour on the network.

For the most cautious, operating on a zero-trust model and assuming all staff have lost their passwords to criminals before is recommended, applying the necessary security measures where appropriate.